ISBRA ESBRA Blog

What Has Neuroimaging Told Us About Addictions?

admin isbra esbra3. June 2016

Leyton M.

Department of Psychiatry, McGill University, Montreal, Quebec, Canada

A large addictions neuroimaging literature has accumulated over the past 20 years, and a number of the findings have been replicated with impressive consistency. In brief, there is evidence that people at elevated risk for addictions frequently exhibit heightened limbic system responses to reward related cues. Once substance use begins, these responses can become pathologically tied to drug cues, plausibly contributing to a gradual narrowing of interests. In the absence of drug cues, limbic cortical-subcortical activity is muted and striatal dopamine release tends to be low, perhaps even actively inhibited. Conversely, in the presence of drug cues, these networks become hyper-activated. Cue-induced activations are most consistently seen in the limbic cortex, amygdala, and striatum, and drug cue-induced dopamine release has now been identified in all three of these sites. Individual differences in susceptibility to developing these environment-dependent cue-induced responses may be related to poor impulse-control and low cortical thickness, dopamine D2 autoreceptors, and serotonergic tone. Finally, two studies suggest that the ability to retain normal dopamine responses in the absence of drug cues is predictive of better outcomes following behavioral therapies. Those who lose the ability to activate limbic circuitry to non-drug rewards might require different treatment strategies.